ALBANY – Environmental activist Robert F. Kennedy Jr., son of the assassinated Robert F. Kennedy, has told friends he may run for New York attorney general next year, sources said last night.

This could put Kennedy, 51, on a collision course with his estranged brother-in-law, former federal Housing Secretary Andrew Cuomo, who also is expected to seek the job.

Cuomo, son of former Gov. Mario Cuomo, is getting a divorce from Kennedy’s sister, Kerry Kennedy. He failed to get the Democratic nomination for governor in 2002.

A crowded Democratic primary for attorney general is expected with Cuomo facing challenges from former Public Advocate Mark Green, Assemblymen Richard Brodsky of Westchester and Michael Gianaris of Queens, and party activist Charlie King.

“If Bobby gets into the race, he would have to be considered a strong candidate,” said King.

But Kennedy, an activist lawyer, doesn’t have a strong Democratic following and could face an uphill battle lining up support, party insiders say.